The use of turbochargers to provide compressed air for internal combustion engines is known. The turbocharger compresses the air, which is then cooled in an intercooler prior to being supplied to an air intake manifold for the cylinders of the engine. The intercooler provides a denser air stream to the engine, which stream is more efficiently combusted, thereby reducing emissions levels of the engine. Internal combustion engines are also known to operate without turbochargers.
Various different engine components are present in the air intake path, including filters, intercoolers, compressors, turbines, and so forth. If any of these devices develops or encounters a restriction of air flow, the air-fuel ratio for the engine is reduced, resulting in increased oxides of nitrogen (NOx) emissions levels and increased fuel consumption.
Accordingly, there is a need for a method and apparatus to detect air flow restrictions.